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TPU (Thermoplastic Urethane)

Typical Machine Settings: Subject To Polymer Grade

Nozzle

Front

Centre

Rear

Barrel Temperature

180 - 220oC

180 - 220oC

175 - 215oC

165 - 205oC

Melt Temperature

185 - 220oC

Must be measured with a pyrometer by taking an airshot through the injection machine nozzle.

Hot Runner Temperature

185 - 220oC

Mould Temperature

25 - 45oC

Run at upper end of range for best surface finish.

Injection Rate

Slow To Moderate

Specific Injection Pressure

350 - 1000 Bar (5,000 - 15,000psi)

Screw Back Pressure

1.0 - 5.0Bar (15 - 75psi)

Screw Speed

20 - 80rpm

Processing Features

Structure

Amorphous

Specific Gravity

1.20

Viscosity

High

Use large runners.

Shear Rate Susceptibility

Medium

Use large gates.

Temperature Window

Medium

Needs fairly accurate & stable control

Residence Time

Medium

Aim for short residence time

Start-Up Precedure
  • Ensure all heaters are thoroughly baked dry - do not rely on brief ‘soft start’ systems to do this.
  • Fast Heat controllers automatically and safely bakeout wet heaters - ask for details.
  • Turn on water lines to stabilise tool and manifold temperatures.
  • Turn on manifold control zone(s) and allow to warm up until measured value is within 10oC of setpoint.
  • Now turn on tip zones and allow to settle at setpoint for 5 - 10 minutes before starting production.
  • Take an airshot from the machine barrel and check that the melt temperature is correct.
  • Start moulding parts on a semi-automatic cycle until suitable machine settings are established.
  • Avoid lengthy delays between cycles during this setting procedure.
  • Switch to automatic cycle when parts are being produced, and fine tune the machine settings

Shut-Down Precedure

The machine and mould may be shut down normally, without purging the TPU from either the barrel or the hot runner.